Geographic Range

Euphydryas editha can be found in scattered, semi-isolated populations in the western United States. Coastal populations range from southern California to western Washington. The species can also be found in locations of the San Bernardino Mountains, Sierra Nevada, higher Cascade Mountains of Oregon to Washington, and in areas of the Great Basin, including central Oregon and the Rocky Mountains. (Radtkey and Singer, April 1995; Scott, 1986)

Physical Description

Euphydryas editha butterflies are usually orange with checkerboard markings; however, their appearance varies based on the area that they inhabit. Coastal populations are black with red and cream spots; mountain populations are red or mottled with red, black, and cream spots. The higher-altitude populations are smaller and darker in color. The larvae of the butterfly are black, spotted with white or orange, or striped with white. The pupae are white or gray, with black blotches and streaks. (Cohen, August 31, 1996; Scott, 1986)

Development

Euphydryas editha eggs hatch about two weeks after they are laid. Larvae live and feed together in loose silk webs, complete three instars, and enter diapause during the spring. Edith's checkerspot larvae have thick and hairy skins to better withstand summer drying during diapause, and can usually be found under stones as they hibernate. The larvae emerge from diapause the following spring, complete development, and pupate. (Osborne and Redak, January 2000; Scott, 1986; Thomas, et al., December 1996)

Reproduction

Once a male spots a resting female, the male lands, nudges under the female's hind wings, and mates with the female, if receptive. A receptive female is passive, while an unreceptive female will reject advances made by males by flapping or trying to escape. (Scott, 1986)

Euphydryas editha are protandrous - males typically emerge four to eight days prior to the emergence of females. The females are able to mate and lay eggs immediately upon emergence from the pupa. Females generally mate once, but are physiologically capable of re-mating four to seven days after their first copulation. Most do not re-mate, however, partly because the male's spermatophore plugs the female's mating tube at least temporarily, and partly because ovipositing females are not attractive to males. Only virgins secrete a pheromone that attracts males. Checkerspot butterflies are univoltine, meaning one generation reaches maturity per year. The eggs are laid in clusters of 20 to 350, and up to 1200 eggs are laid per female lifetime. (Baughman, August 1991; Scott, 1986; Thomas, et al., December 1996)

Lifespan/Longevity

Adult Edith's Checkerspot live about ten days, on average.

(Baughman 1991)

Behavior

Euphydryas editha are very sedentary - individuals do not move more than 600 meters, or 2000 feet, in their entire lifespan. Perhaps because of this, there are many phenotypically well-defined groups that rise from preferences for different combinations of host plants existing in close proximity of one another. Very little gene flow occurs between these populations. Adults make one flight during March to April on the California coast, June in the Great Basin, and late June to early August above the timberline. (Britten, et al., 1995; Sbordoni and Forestiero, 1998; Scott, 1986)

Communication and Perception

Checkerspots are known to communicate at least on the chemical level. Virgin females release a pheromone which attracts males, allowing them to be located in order to mate. Unseen virgins are typically found by a male after about an average of fifty minutes. Males also contact females prior to copulation. (Scott, 1986)

Food Habits

Edith's checkerspots prefer herb host plants from the families Scrophulariaceae, Valerianaceae, Plantaginaceae, and Caprifoliaceae. However, most populations of this butterfly are monophagous, and the preference is based on location. Egg-laying habits, larval host preference, and movements are locally adapted, and for that reason, the survival of Euphydryas editha depends upon the growing season of its host plants. The differences in host preferences are genetically based. Diet evolution in Euphydryas editha can be very rapid. Adult butterflies seek nectar and seem to prefer yellow or white flowers. The host plant flowers are never visited, apparently because the butterfly's proboscis is too short. (Cohen, August 31, 1996; Osborne and Redak, January 2000; Radtkey and Singer, April 1995; Scott, 1986)

Predation

Checkerspot butterflies have developed defense mechanisms to prevent predators from attacking. Larvae twitch in unison to repel predators, and, depending on the host plant of the population, the larvae, pupae, and adult butterflies are somewhat poisonous to vertebrates because they may injest toxins from the plant. (Scott, 1986)

Ecosystem Roles

Populations of Euphydryas editha use several different hosts to house and feed their pupae. Though they usually do not pollinate the flowers of the host, larvae have been known to eat the leaves, the flowers, and sometimes the entire host plant, and have starved trying to find another. (Radtkey and Singer, April 1995; Scott, 1986; Thomas, et al., December 1996)

Ecosystem Impact

pollinates

Economic Importance for Humans: Positive

In order to obtain nectar, adult Euphydryas editha sometimes pollinate various flowers in the area of their habitat. (Scott, 1986)

Economic Importance for Humans: Negative

Edith's checkerspots lay their eggs on various plant species, sometimes resulting in the death of the host plant, which could be economically important to humans.

Larvae, pupae, and adults are poisonous to vertebrates if ingested. (Scott, 1986)

Conservation Status

Euphydryas editha populations mirror the changes in climate over long periods of time. Global warming is expected to eliminate the butterflies in the south, where the season is short and growing shorter. About three-fourths of the populations living in the lowest latitudes have become extinct. In Canada, however, less than twenty percent have disappeared. The sedentary checkerspots remain at their original habitat despite human interferences, and evolve adaptations to deal with these changes, thus making them dependent on the continuation of the human interference. This dependency results in insects that refuse to accept their ancestral host. In January of 1997, the subspecies Euphydryas editha quino and Euphydryas editha bayensis received federal protection under the Endangered Species Act. Euphydryas editha bayensis has also been given the Nature Conservancy Global rank of T1, which means that there are very few individuals remaining. (Cohen, August 31, 1996; Osborne and Redak, January 2000; Singer, et al., December 16, 1993; Struttmann, 2004)

Other Comments

In the past thirty years, Edith's checkerspots have suffered two major crises. In 1967, humans cut down patches of a forest inhabited by the butterflies. The butterflies were able to adapt, and began to lay eggs on a new host with a high rate of breeding success. In 1992, a severe summer frost killed the new host, and checkerspot larvae starved. At least 21 subspecies of Euphydryas editha exist. (Miller, 1992; Thomas, et al., December 1996)

Contributors

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

diapause

a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nectarivore

an animal that mainly eats nectar from flowers

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

Disclaimer:
The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.